My guess is the original controls crapped out and somebody replaced the motor starter and put a massively oversized supply cable on it. Does the motor appear to be the original vintage? I bet there is a tag on it that you could find with a cellphone or a mirror and a flashlight. I wouldn't put much stock in a $100 phase converter but what do I know? A good quality phase converter is a good investment and will make possible future similar acquisitions. If you can get that machine going and it's not thrashed it will be a great planer, pretty near invincible one might say.
Link to Philip Mitchell's post on his S50
https://sawmillcreek.org/showthread....0-planer/page5 There is another on the same machine entitled "Italian Arn acquired" on owwm.org